Furnace and grate ttiterefor



Fem 12 392410- VV @.DOBES- FURNACE AND v@TRATE THEREFOB rFiled April 16. l925 S14/umd o@ Patented Feb.` l2, 1924.

uuiTED STATES PATENT OFFICE.

WILLIAM e. DoBBs, or AUBURN, NEW YORK.'

FURNACE AND GRAT TEBEFOR.

Application led April 16, 1923. .iSerial No. 632,409.

To all 'whom t may conce/ra: y

Be it known that I, l/VILLTAM G. Dos, a citizen of the United States,'residing at Au burn, in the county of Cayuga and State of New Yorl-t, have invented certain new and useful Improvements in Furnaces and Grates Therefor, of which the following is 'a speciication, reference being had to the accomscreenings, these being a necessary byprodi' uctjof everyanthracite coal mine and being capable of being bought at from one-third to one-fourth the priceof the larger sizes such as egg, stove, 'nut and pea.

A further object is to provide a furnace having therein a grate so formed as to be capable of burning euhn in combination with means for forcing air into the ash pit of the `furnace and up through the gate to thereby entirely vconsume the coal on the grate.

A still further object is to provide agrate of a very simple characted adapted to be made in sections and thereby' befdisp'osed within lan ordinary furnace in vplace of the ordinary grate or initially disposed in said furnace, these sections of the grate being disposed in, tight abutting relation to each other and' each section of the grate being lformed with a plurality of apertures fitted with removable perforated plugs through' which the air will pass up through the grate and through the coal lying thereon. Another object is to provide a grate having air apertures so arranged as to blow the air blast from practically every angle, thus securing an even fire all over the grate, there being no deadspots or zones ofineoinplete combustion in the coal.

Still another Objectis to provide a grate formed in sections and means for locking the grate sections together into such abut-4 tingrelation that. no air can pass upward between the grate 'sections- A further object is to provide a grate which may be installed without anyhchanges or alterations in the boiler of the'heater.v

Other objects will appear in the course of the following description.

My invention isillustrated inthe accompanylng drawings, where1n:-

Figure 1 is a front elevation of a furnace' with my improved grate appliedthereto;

Figure 2 is an enlarged section on the line v2 2 of Figurel Figure 3 is a fragmentary vertical section through a portion of the furnace and-my imi proved grate; i

Figure 4 is a fragmentary perspective View of one of the grate bars;

Figure 5 is an enlarged vertical sectional view through one of the plugs;

Referring to th drawings, A designates an ordinary boiler furnace, though it is to be understood that my invention is not limited to a boiler furnace but may be used in connection with any furnace as, for instance, a house heating furnace, whether using hot air, steam, vapor or hot water. This furnace is'usually provided with a grate disposed between the tire box and the ash pit this grate being ordinarily of Such character that it may be shaken so as to discharge ashes into the ash pit', the ashes being.

removable through the door opening 'closed by the door b.

My invention consists in disposing. within the furnace betweenthe fire box and the ash pit a grate of the construction shown in detail in Figure 3. This grate consists of a plurality of sections 10 which in Figure 2 are shownas elongated bars. These sections may be made of any length and are rectangular in cross section so as to provide lateral faces which may be abutted close against eachother and in air-tight contact. These sections 10 at their opposite ends are formed with the transversely extending grooves or channels 1.1 for the 'receptionof a locking bar 12, this locking bar'having nuts 13. ll7hen this locking bar is .forced ,down into these grooves the sections are clamped in close airtight engagement with each other and held from any movement `which would tend to separate the sections close fit in the aperture 11i and the periphery of the plug is formed with a longitudinally extending series of grooves 16 opening upon the periphery bf the plug, these grooves preferably being semicircular and being placed relatively close together. The body of the plug is formed with a plurality of openings 17, which openings are downwardly flared. It will be noted that the grooves 16 at their lower ends approximate the outer surface of the plug, this be t0 ing due to the fact that the plug tapers from its large end tol its small end When the plug is in place within the circular aperture 14, the grooves 1G form air holes and the air in the ash pit may pass upl ward and through thev holes 1G and 1T into and through the mass of coal supported upon the grate. These apertures 16 and 1T at theirnpper ends are of such small size that they will prevent even the smallest` 20 coal of commercial sizes from dropping downward througli the grate.

Obviously the form of the grate will depend upon the form of the furnace with which the grate is intended to: be used.

znThe grate made up of the sections may be round, rectangularfor oval in form and the 4sections will, of course, conform to the shape of the grate. Y,l may use gratos of `any shape and I do'inot wish to be limited to the 'particular form of grate illustrated in Figure 2.

The gratos are to be disposed upon a concrete or other non-heat-coiulucting, airtight wall 1S which extends upward from the bottom of the ash pit entirely around the furnace, as shown in Figure so that the graterests upon the concrete and the concrete se-als the grate and prevents air from leaking 4up around the edges thereof.

4o Boiler cement may also be applied. as at 1 9, around the edges of the grate and above the. concrete 18 so as to additionally seal the grate against leakage of air around its periphery. Preferably the grate formed of the pairs of sections 10 is relatively thick, but obviously I do not, wish to be limited to t-his, it being also advisable that the grate bars 'shall be of such area in cross sectionas to prevent the bars being warped by iu- 50.tense heat.

Extending into the ash pit of the furnace and sealed by the concrete 18 is an air pipe 20 which leads to a blower 21 which may bev operated by any suitable motor or power from any source. The blower is intended to be of a size proportionate to the capacity of the fu-rnace and for the work designed to be done. lVhen the door L is closed, it is obvious that all ofthe air forced into the ash pit of the furnace will be forced up through the small perforation 1G and 1T and forced through the fire bed. This causes the almost complete combustion of the coal upon the grate so that actual tests U5 with this form of grate have shown that the rasage? ash contains less than 5% unburned carbon, whereas in the normal furnace the unburned carbon will run from 18% to 60%, thus not only Wasting the cost of the uuburned coal but also increasing the cost of removing the ashes. ln furnaces constructed in accordance with my invention all ashes removed are in the forrli of clinker. The high heat fuses the ash directly oyer the plugs and then over the whole bed of the fire and thus burns prac-ticaly all the Carbon out of it; As a consequence, the clinker never adheres to the grate and. as a mattei' of fact, is easily broken with a slice bar andremoved with ton'gs through the fire door. Thus actual practice has shown that this is a. very easy operation, much easier thairthe ordinary method of cleaning by shaking the grate and removing the dusty ashes from the pit. All dust stays in the furnace and falls back into the grate to beeompletely burned and to form a new clinker.

lt will be noticed that in my constriiction the holes in the plugs are. extended downward 'so that any small particles of dust which may get into these holes will fall through freely into the ash pit. All particles lodging in them become fused with the soft clinker and are drawn out with it, but some dustfalls through andy it is necessary to remove this dust through the. ash pit. As a matter of fact, `these apertures 16 and 17 do not choke up at all and this has been demonstrated by tests of this grate.

It will be seen that this grate eliminates the great losses in operating boilers equipped with grates yas it eliminates the loss 'from unburned carbon in stack gases and smoke, this loss being estimated to amount to aslO much as 35%. it eliminatesthe unburned combustible leftin the ash, and prevents unburned coal from dropping through the gratos. All these losses result from poor Combustion and bcause the grate bars are separated sufficiently to permit the dropping down of small pieces of coal into the ash pit. By my construction the air is not merely passed through the coal without becoming thoroughly mixed with it as it does where ordinary grate bars are used and forced draft, but the air is thoroughly mixed with the coal `in its upward passage. rlhus there are no blow holes or dead' spots in the fuel bed and as a matter of fact the coal gas it- 120 self is burned with the smoke and soot from the stack and these losses are thus eliminated. A furnac'e having my Vimproved K, grate burns the lower grades of hard coal,

thus reducing the initiallcost ofthe ooaland i as it burns the coal more' completely it requires fewer tons of'coal to secure the samevv heating result. A fullbodied flameuis produced because suficientogygen isboth sup-.- plied and mixed withl-the fuel and gases to ing out the furnace.

"this invention it has low and cooling the grates by water.

r grates leaking,

combine all the carbon while it is still in the combustion chamber. It is particularly adapted to meet the peak load as the forced draft may be applied either automatically or by hand at a given time and immediately after the forced draft is applied the rate of combustion increases and this causes an immediate rise of heat. Furthermore, it will be seen that it simplifies firing, and as it* requires'less coal requires less work by the fireman. rlhe volume of ash is very greatly reduced and there is less necessity for clean .lt will be seen that tlie air becomes heated in the sealed ash pit which has been converted into an air chamber so that this air enters ythe fire box at a temperature much higher than that of the boiler room. A large volumev of flame is produced over the coal at all times, thus burning all the gases arising from the coal. The fires, however, can be banked almost instantly, all that is required being to shut ofi the motor of the blower and the fire immediatel i dies down. On the other hand, the lires a ter being banked for a suitable time can be started up instantly. No waiting is necessary as there. is where natural draft is used.

There is one other point of particular importance in this grate, that is that it is air blast cooled. rlhe'A cold air blast striking against the under face of the grate makes this grate warp-prooi?,y thus doing vaway with the necessity of making the grateslholtuin.. thermore, where a grate is water-cooled, it is very diiicult to form airpassages extending through the grate bar and where the grates happen to be disposed inside the water leg of the boiler the water leg ofthe boiler must be drilled or otherwise formed for the water connections, which is difficult' and makes the use of such a grate very limited. Furthermore, there isV always danger of the letting water out, and if the water should run back any while the grates are hot they will split and crack. It 1s obvious that there `is no danger of this character with my improved grates.

ln actual practice the grate is made of narrow bars about 5" wide and t thick, thus making it possible to installjthe grate in any type of heater or.. power plant, and the grate may be installed either in heaters 'with small doors or heaters of peculiar types or shapes. Y i

ln grates constructed infaccordance with been found that the screenings or culm is 'so completely burned' that the fuel fuses together in a clinker over the whole grate, this clinker being usually about two inches thick. By inserting a slice bar underneath this clinker it may be lifted up and then will ordinarily break in from two to six pieces. f rlhe side next the]y grate is, of course, black and the top of this clinker usually red hot. By turning the pieces over all the good fire or live coal will drop off and by leaving the pieces of clinker near the door for two or three minutes they are ready to come out. This is all that is necessary to do in orderv to clean out the grate and there is no necessity for the removal of ashes, as there is in an ordinary grate. As soon as the clinker is removed the fire is again like new.

Whilel have illustrated the grates as being supported upon a concrete, or cement supporting wall, I do not wish to be limited to this, as it is obvious that the grates might be mounted on metallic frames to support them -any desired height. The vone-inch space around the grate is thensealed to make air-tight. Any cracks or openings are also sealed with cement to maks the ash pit tight. This eliminates the building of concrete forms and simplifies the installation of the grate. y'

One of the features which I .desire partieularly emphasized is that the fire may be forced to its limits or to any desired or necessary degree and that thus l am able to increase the capacity of the plant at least one-third and in some cases twice, or in other words secure work from one boiler which would formerly take two under natural draft.. It may be stated that in actual practice it has been found that with grates of the character described and blowers blowing theair through the fire that the temperature of the water in a hot water heating system may be raised from 80 to205 in fifty-five minutes-,whereas this usually requires from two and a half to three hours where only natural draft is used.

l. lin a furnace, a grate formed of a plurality of parallel, laterally abutted sections, each section having air apertures therethrough, all of said sections at their opposite ends having transversely extending, aligned grooves, locking bars extending transversely across all of said sections adj acent the ends thereof and disposed in said grooves, the locking bars having heads wider than the grooves and engaging the outer faces of the end sections. A

2.. As an article of manufacture, a solid grate bar,'rectangular in cross section, and

'having flat sides and upper and lower faces,

the grate bar being formed with a plurality of apertures extending entirely through the grate bar, the vapertures, :being downwardly tapering, downwardly tapering plugs disposed in said apertures and fitting closely against the walls of the apertures, each plug having. a plurality of openings extending entirely through the plug. y

3. As an article of manufacture, a solid grate bar, rectangular in cross section having flat sides and flat upper and lower faces, the grate bar being4 formed with a plurality of apertures extending entirely through lthe grate bur and from face thereof, each 'aperture being downwardly tapered, downwardly tapering plufrs disposed'in said apertures und fitting close y the upper to the lowerI against the Walls thereof, each. plug having peripheral, longitudinally extending grooves, and u plurality of openings extending en- 10 tirely through the plug from end to end.

ln testimony whereof I hereunto afx my signature. I 1

/VUJLIAM G. DQBBS. 

